In a recently issued patent (U.S. Pat. No. 4,996,508), the spatial and temporal control of magnetic fields within solenoids was taught. I am not aware of efforts to modify the magnetic field outside a solenoid, except for screening of such fields by using highly ferromagnetic substances which concentrate the fields within these ferromagnetic substances.
In yet another recently issued patent (U.S. Pat. No. 5,010,311) the general principle of using switchable superconducting elements to obtain modulation of magnetic fields in the vicinity of said elements was taught. In the aforementioned copending application (Ser. No. 07/314,427) entitled "Switchable Superconducting Elements and Pixels Arrays" modulation of magnetic fields on a point by point basis was described.
The present invention provides for modulation of magnetic fields outside solenoids as well as additional means for obtaining new magnetic field topologies within solenoids and controlling these by mechanical and electronic means.
Prior art design of a superconducting magnetic energy storage (SMES) system has been limited by the hoop stress on the solenoid windings induced by the interaction between the magnetic field generated within the solenoid and the current in the solenoid windings which can be alleviated by the invention.